1. Field of the Invention
The present invention relates to an inclination setting rotational laser apparatus for use in a laser surveying instrument in which a laser light beam can be projected with a tilt angle with respect to a level plane.
2. Description of the Related Art.
There has been available a rotational laser apparatus such as shown in Japanese Patent Laid-Open gazette No. 6-26861, for example. According to the rotational laser apparatus, as shown in FIG. 12, a laser beam can be projected rotationally so as to form a laser reference plane. Further, the arrangement shown in the figure allows the laser reference plane to be tilted.
That is, a laser projector 10 is disposed at substantially the center of a casing 5, and a rotational scanning unit 13 is provided above the laser projector 10. The rotational scanning unit 13 is arranged to be rotatable in the horizontal direction by means of a scanning motor 15 through gears. A pentaprism 18 is provided in the rotational scanning unit 13, so that the laser light beam irradiated on the rotational axis of the rotational scanning unit 13 is polarized by 90 degrees to form the laser reference plane.
The laser projector 12 and the rotational scanning unit 13 are arranged to be tilted in two directions perpendicular to each other. The laser projector 12 is provided with a first inclination sensor 20 and a second inclination sensor 21. The first inclination sensor 20 and the second inclination sensor 21 are disposed so as to intersect each other at right angles.
Further, the laser projector 12 is provided with a first setting inclination sensor 65 and a second setting inclination sensor 66. The inclination directions of the first setting inclination sensor 65 and the second setting inclination sensor 66 are made to agree with the two directions perpendicular to each other in which the first inclination sensor 20 and the second inclination sensor 21 extend, respectively. Thus, the laser projector 12 can be inclined with respect to the position determined by the first setting inclination sensor 65 and the second setting inclination sensor 66.
The first setting inclination sensor 65 and the second setting inclination sensor 66 are provided on a base plate and the inclination angle can be arbitrarily set by means of a first arbitrary angle setting unit 52 and a second arbitrary angle setting unit 53 (not shown).
The first arbitrary angle setting unit 52 and the second arbitrary angle setting unit 53 are arranged to be driven by a first tilting motor 58 and a second tilting motor 59 (not shown) through a gear.
The casing 5 is provided with a first inclination setting unit 35 and a second inclination setting unit 36 (not shown). The first inclination setting unit 35 and the second inclination setting unit 36 are utilized to incline the laser projector 12 and the rotational scanning unit 13 so that the directions of the first inclination sensor 20 and the second inclination sensor 21 are perpendicular to each other.
The first inclination setting unit 35 and the second inclination setting unit 36 are driven by a first inclination adjusting motor 31 and a second inclination adjusting motor 32 (not shown) through a gear.
The laser projector 12 has a first arm 25 and a second arm 26 (not shown) extending therefrom in a direction perpendicular to the laser projector 12 The first arm 25 and the second arm 26 are engaged with the first inclination setting unit 35 and the second inclination setting unit 36, respectively.
When an inclination is set in the apparatus, the laser reference plane is made to agree with the horizontal plane for setting the reference position. The tilting mechanism corresponds to tilting means.
When the horizontal plane is set in the apparatus, the horizontal position is detected by the first inclination sensor 20 and the second inclination sensor 21. At this time, the rotational axis of the rotational scanning unit 13 is made vertical and the first setting inclination sensor 65 and the second setting inclination sensor 66 are made horizontal.
Then, the first arbitrary angle setting unit 52 and the second arbitrary angle setting unit 53 are driven based on the tilting angle inputted through inputting device so that the first setting inclination sensor 65 and the second setting inclination sensor 66 are inclined in the negative direction with respect to a predetermined inclination angle.
After the first setting inclination sensor 65 and the second setting inclination sensor 66 are inclined in the negative direction, the first inclination setting unit 35 and the second inclination setting unit 36 are driven until the first setting inclination sensor 65 and the second setting inclination sensor 66 indicate the horizontal state with their output signals, whereby the laser projector 12 and the rotational scanning unit 13 are inclined. When the first setting inclination sensor 65 and the second setting inclination sensor 66 indicate the horizontal state with their output signals, the inclination setting operation is completed.
FIG. 13 is a diagram showing a control block for controlling the apparatus.
The first fixed bubble tube 20 and the first arbitrary angle setting bubble tube 65 supply detection results through a first switching circuit 85 to a first angle detecting circuit 87 while the second fixed bubble tube 21 and the second arbitrary angle setting bubble tube 66 supply detection results through a second switching circuit 86 to a second angle detecting circuit 88.
The first angle detecting circuit 87 and the second angle detecting circuit 88 have a reference angle 91 and a reference angle 92 set therein, respectively. The reference angle 91 and the reference angle 92 are set to zero in the ordinary state.
When the first angle detecting circuit 87 is supplied with a signal from the first fixed bubble tube 20 through the first switching circuit 85, the first angle detecting circuit 87 detects a deviation amount relative to the reference angle 91. Then, the first angle detecting circuit 87 supplies a signal to a first motor controller 89 and a first level adjusting motor 31 is controlled by the first motor controller 89.
When the first angle detecting circuit 87 is supplied with signals from the first fixed bubble tube 20 and the arbitrary angle setting bubble tube 65 through the first switching circuit 85, the first angle detecting circuit 87 generates a signal corresponding to the deviation amount. Then, the signal indicative of the deviation amount is supplied to a first inclination drive circuit 83, and a first drive motor 58 is controlled in its drive by the first inclination drive circuit 83. Further, when the second angle detecting circuit 88 is supplied with a signal from the second arbitrary angle setting bubble tube 66 through the second switching circuit 86, the second angle detecting circuit 88 detects a deviation amount relative to the reference angle 92. Then, the second angle detecting circuit 88 supplies a signal to a second motor controller 90 and a second level adjusting motor 32 is controlled by the second motor controller 90.
The signal of the second angle detecting circuit 88 is supplied to the second motor controller 90, and the second level adjusting motor 32 is controlled in its drive by the second motor controller 90. Then, the signal of the second angle detecting circuit 88 and the signal of an arbitrary angle setting circuit 82 are supplied to a second inclination drive circuit 84, and a second drive motor 59 is controlled in its drive by the second inclination drive circuit 84.
Then, the angle deviations generated from the first angle detecting circuit 87 and the second angle detecting circuit 88 are supplied to a discriminator 93. The discriminator 93 selects the larger angle deviation from the angle deviations of the first angle detecting circuit 87 and the second angle detecting circuit 88, and supplies an output corresponding to the selected angle deviation change to a display driver 94. The display driver 94 makes a display 95 display corresponding to the value of the deviation.
According to the present embodiment, the reference plane formed by the laser beam can be set horizontal or inclined by an arbitrary angle. Now, the leveling operation of the laser surveying instrument for forming the horizontal reference plane will be described.
If a main unit 4 is installed and no adjustment is carried out, the axis of the laser projector 10 does not coincide with the vertical line in general, and hence the first fixed bubble tube 20 and the second fixed bubble tube 21 are not horizontal.
The first switching circuit 85 establishes a signal line from the first fixed bubble tube 20 to the first angle detecting circuit 87 while the second switching circuit 86 establishes a signal line from the second fixed bubble tube 21 to the second angle detecting circuit 88.
If the reference angle 91 is set to zero, the first angle detecting circuit 87 generates an angle deviation signal while if the reference angle 92 is set to zero, the second angle detecting circuit 88 generates another angle deviation signal. When the angle deviation signal is generated, the first motor controller 89 and the second motor controller 90 drive the first level adjusting motor 31 and the second level adjusting motor 32 in a predetermined direction so that the angle deviation signal becomes zero.
The laser plane formed by the rotational laser apparatus is required to have a high inclination precision because the laser plane serves as a reference plane. A pendulum type inclination detecting apparatus can detect the inclination angle at relatively wide detection range. However, the pendulum type inclination detecting apparatus includes a mechanical drive portion and therefore the detection precision is influenced from the frictional drag and it is very difficult to detect an angle in unit of several seconds.
As a conventional element for detecting the inclination of a surveying instrument, an electric type bubble tube 10000 as shown in FIG. 14 has been utilized.
The bubble tube 10000 has a bubble 5000 enclosed therein and electrodes 6000 and 7000 formed thereon so that the electrostatic capacitance can be measured in an electric manner to determine the inclination of the apparatus.
The electric type bubble tube 10000 is formed of a hollow glass tube and liquid and the bubble 5000 are enclosed therein. The electrodes 6000 and 7000 are formed on the outside of the glass tube and there is no mechanical drive portion, so that the electrostatic capacitance can be detected precisely by using the shifting motion of the bubble.
When inclination is detected precisely by using the bubble tube system, it is requested that the glass tube has a large radius of curvature. However, the bubble tube of a glass tube having a large radius of curvature offers only a small detection range and moreover is expensive.
Further, the bubble tube of a glass tube having a large radius of curvature offers only a narrow dynamic range for detecting the electrostatic capacitance, which limits the detection range to only around horizontal. Therefore, in order to settle an inclination with high precision, it is necessary to employ a fixed sensor and a setting inclination sensor. Further, if it is requested to detect inclination in two directions, four inclination sensors are necessary.
Furthermore, an arbitrary angle setting unit comes to have a complicated structure, serious problems are expected that error is caused from abrasion or error in motion is caused from friction.
According to the present invention, there is provided an arrangement in which a laser projector projects a laser beam, tilting means tilts the laser projector in at least one direction, a first optical system of inclination detecting means directs the light from a light source toward a liquid member having a free surface, light receiving means receives the light reflected on the liquid member, a second optical system guides the light reflected on the liquid member to the light receiving means, and arithmetic operation means calculates the inclination based on the received signal of the light receiving means, whereby the laser projector can be settled to have an inclination by driving the tilting means based on the inclination.
Further objects and advantages of the present invention will be apparent from the following description which is given with reference to the accompanying drawings wherein preferred embodiments of the present invention is clearly shown.